The following comments or queries have been submitted by visitors, but may have been edited slightly to allow for space.

Rick (UK): I've read Virolution and really enjoyed it. But I'm not a scientist. Am I right in thinking that the whole theory of evolution needs to be radically changed to take on board the new ideas, such as symbiotic viruses and epigenetics. Is this what Frank Ryan is suggesting?

F.R.: Not really. The concepts of evolutionary biology are changing, but this doesn't involve throwing out the classical basis. The newer concepts are like adding new chapters to an existing book, whether of evolutionary biology or the genetic basis of medicine. Viral symbiosis and the broader umbrella concept of genomic creativity expand our knowledge base in important ways but these are complementary to the rest of the book.

Lady visitor (Ireland): I heard you speak about your book on the Pat Kenny Show. I'm 28 and was just recently diagnosed with MS. I'm just about to see my neurologist and will talk to him about your book. Is there going to be a cure soon?

F.R.: You have my sympathies - but as a doctor I never interfere with another doctor's management or therapy. The new research on MS does not, in itself, amount to a cure, but it's encouraging in the sense that it offers a potential explanation of how beta-interferon helps patients (in the past we just weren't sure) and it also suggests that the present treatments are on the right lines. What the new research is about is offering us a much closer understanding of what is causing MS. This is vital to the search for better treatments, and, in time, the possibility of a cure.

Janet (New Zealand): I'm a grad student in zoology. I haven't read Virolution as yet but probably will. Where do I get hold of the science papers that back up the new ideas that Frank Ryan has written about in Virolution?

F.R.: There are extensive references to my own papers, and those of others, such as Professor Luis Villarreal, Professor Marilyn Roossinck, and many others, in the reference section at the end of the book. The five review papers in the J of the Royal Society of Medicine are written but still in the process of being published and these contain many hundreds of scientific references. For example the paper on the autoimmune diseases, including MS, should be published by October. They should all be published by the end of 2009. Scientists and medics can make contact with me via the contact page so I can provide some of these references or point people in the right direction to obtain them.

Marcus (US): I'm not a scientist but I like to read about science. Was it really necessary to make such a great story kind of jazzy and artsy? Why not just write it plain and simple, like a series of lectures?

F.R.: When I write scientific papers, or deliver a lecture to colleagues, I stick to being objective and factual. But when I write a popular science I try to entertain as well as inform. If I wrote the book in the way you suggest, it would be very difficult to get a publisher to take on the risk of publishing it - a popular science, book, just like a novel, has to sell to a wide variety of readers. Sometimes this can create a genuine dilemma for the writer - but with Virolution there was no such problem since I had already written, or was in the process of writing, a lengthy series of scientific articles that explained the new evolutionary concepts to a scientific readership.

Marco (Italy): I'm a biologist who teaches evolutionary biology to undergraduates. I read Virolution with great interest and will certainly incorporate the new ideas into my curriculum. The concept of viral symbiosis is completely new to me and it will now become an important component of my lectures. But the author does not present modern Darwinism in the broad way that, for example, Coyne and Orr do in their book, Speciation. Was this a deliberate omission?

F.R: Thanks for the kind comments. You're right. I made no attempt to cover modern Darwinism in detail, though I did devote a chapter to it early on to make sure people were aware of what I was not covering in detail. Just about every other book out there goes to town on modern Darwinism, which I acknowledge to be important, but my brief in Virolution was to cover the four main mechanisms of generating hereditary change, and in particular to explain my role in developing the concept of viral symbiogenesis. The latter has never been covered in a book before. I doubt that any one book available at the moment will cover all of modern evolutionary biology, even for lay people. One needs to read at least two or three to get a broad overall picture.

But experts like you are welcome to get in touch via the contact page if you want more details of scientific papers on viral symbiosis.

James (UK-based doctor): I loved the book but disagree on an important point. Dr Ryandevelops two big themes, the viral symbiosis theme, which was a revelation to me, but also the broader theme he calls genomic creativity, which includes four different ways in which evolution gives rise to hereditary genetic change. He also says that natural selection is not a big consideration for medicine. This seems to contradict what we previously took for granted. surely this has to be wrong?

F.R. I wouldn't dream of dismissing the importance of natural selection to evolution. I respect and admire Darwin's great theory, which remains the foundation stone of evolutionary biology. What I actually say is that natural selection, while a vitally important force in human evolution, is somewhat tangential to day-to-day medicine. If it were of major practical interest to medicine, it would be taught as such in every medical school, whereas in reality it is hardly covered at all in most - at least to my knowledge. This doesn't imply that it is unimportant but results from the fact natural selection is relatively slow-moving and applies more to populations than to individuals on a day to day basis. But the forces for hereditary change, mutation, genetic symbiosis, hybridisation, and epigenetics, do very much work at individual level and in a day to day way. They are the same forces that operate as the genetic and epigenetic underpinning of the common diseases. That makes them important to medicine.